小腿电阻抗比值评价透析患者容量对改善高血压的作用

目的 用小腿电阻抗比值（calf-RBI）评价血液透析（HD）患者容量状况，观察容量负荷过重者在calf-RBI指导下降低干体质量对血压的作用。 方法 应用多频生物电阻抗分析仪测量小腿电阻抗，以calf-RBI=200 kHz电阻抗/5 kHz电阻抗为容量负荷指标。根据健康对照组各年龄层的calf-RBI确定正常参考范围。降低calf-RBI增高者干体质量，观察calf-RBI、血压和降压药用量等的变化。 结果 calf-RBI在健康对照组和HD组均呈正态分布，与性别、BMI无相关，仅与年龄呈正相关（健康对照组r = 0.269，P ＜ 0.01；HD组r = 0.486，P ＜ 0.01）。117例HD患者中，42例（35.9%）透析后calf-RBI高于正常参考范围，其未控制的高血压的发病率为59.5%，明显高于calf-RBI正常者的33.3%和calf-RBI降低者的16.7%（P ＜ 0.01）。calf-RBI增高者降低干体质量后，calf-RBI明显降低至正常参考范围（P ＜ 0.01），未控制的高血压的发生率从74.1%下降至33.3%（P ＜ 0.01），降压药用量也较前减少（P ＜ 0.05）。 结论 小腿电阻抗比值作为评价容量负荷的一种指标，符合生理学原理，与临床表现有良好相关性，有助于识别和纠正HD患者慢性容量过负荷，改善容量相关高血压。

Effect of calf bioimpedance ratio for volume evaluation on hypertension in hemodialysis patients

Objective To elucidate the effect of bioimpedance ratio in the calf (calf-RBI) for volume evaluation on hypertension in hemodialysis (HD) patients. Methods Bioimpedance in the right calf was measured by bioimpedance spectroscopy (BIS). As an index of volume status, calf-RBI was calculated as follows: calf-RBI =impedance at 200 kHz / impedance at 5 kHz. The range of age-stratified 1SD from mean calf-RBI in the healthy control was assumed as the target range for the corresponding HD patients. The dry body weight (DBW) was stepwise decreased under the guidance of calf-RBI. The changes of calf-RBI, blood pressure and antihypertensive medications were recorded and correlation analysis among indexes was performed. Results The calf-RBI showed a normal distribution in both healthy subjects and HD patients. The calf-RBI was positively correlated with age, but not with gender or BMI. Forty-two patients with (35.9%) calf-RBI beyond target range were identified in 117 HD patients. The percentage of uncontrolled hypertensive individuals was significantly higher as compared to those with calf-RBI within or below target range (59.5% vs 33.3% and 16.7%, P＜0.01). The percentage of uncontrolled hypertensive individuals and the dose of antihypertensive medications was significant improved after decreasing the DBW in the patients with calf-RBI beyond target range (74.1% vs 33.3%, P＜0.01) and defined daily dose (2.00±2.28 vs 2.49±2.47, P＜0.05 ). Conclusions The age-stratified calf-RBI may be used as a useful index for estimation of volume status, and has a good association with clinical manifestations. Recognition and correction of chronic fluid overload based on age-stratified calf-RBI is helpful in hypertension control for hemodialysis patients.